Comment by ValdikSS

Baikal definitely has anti-rollback, and Loongson should have it too. That's a common feature.

As of efuses, they are present essentially anywhere. In any SoC and microcontroller. They are usually used to store secrets (keys) and for chip configuration.

The linked wiki article written in a way that the reader might assume that OnePlus did something wrong, unique, anti-consumer, or something along the lines. Quite the contrary: OnePlus issued updated official firmware with burned the anti-rollback bit to prevent older vulnerable official firmware from being installed. Either new bootloader-level vulnerability has been found, or some kind of bootloader-level secret has leaked from OnePlus, with which the attacker can gain access to the smartphone's data it should not have. By this update, OnePlus secured data of the smartphone owners again.

You still can unlock the bootloader and install custom firmware (with bumped anti-rollback version in the firmware metadata I guess, that would require newer custom firmware or a recompilation/header modification for the older). Your device with the custom firmware installed won't receive the official firmware update to begin with, so it could not be bricked.